Irradiation Effects During XPS Studies of Cu(II) Activation of Zinc Sulphide

The surfaces of zinc sulphide particles after copper(II) activation at pH 9 have been studied by x-ray photoelectron spectroscopy. The influence of x-ray irradiation time on the forms and intensities of the photoelectron signals from zinc sulphide particles activated at various copper coverages was investigated. High binding energy components and satellites of the Cu 2p signals, characteristic of copper(II) hydroxide overlayers, reduced in intensity with increased x-ray exposure. An associated reduction in the concentration of surface oxygen was also observed. Differential charging analysis and curve fitting reveal the dehydration of Cu(OH)2 to CuO, followed by photoreduction of CuO to Cu2O. No evidence was found for x-ray irradiation enhancement of continued Cu activation of or diffusion into ZnS.